CN113107732B

CN113107732B - Needle valve matching part of common rail fuel injector

Info

Publication number: CN113107732B
Application number: CN202110565125.9A
Authority: CN
Inventors: 张涛; 乔信起; 孙春华; 徐光平; 王�华
Original assignee: FAW Jiefang Automotive Co Ltd
Current assignee: FAW Jiefang Automotive Co Ltd
Priority date: 2021-05-24
Filing date: 2021-05-24
Publication date: 2022-04-15
Anticipated expiration: 2041-05-24
Also published as: CN113107732A

Abstract

The invention discloses a needle valve matching part of a common rail oil sprayer, and belongs to the technical field of oil injection systems. Common rail injector's needle valve idol spare includes the needle valve, needle valve body and elasticity module, the needle valve is located the needle valve internally, form the pressure chamber between the inside of needle valve body and the bottom of needle valve, the bottom of needle valve body is equipped with a plurality of nozzle openings, the circumference direction setting of pressure chamber is followed to a plurality of nozzle openings, the elasticity module sets up the bottom at the needle valve, be equipped with a plurality of oil outlets along circumference direction distribution around the elasticity module, be equipped with the high-pressure oil duct in the needle valve, the export and a plurality of oil outlet of high-pressure oil duct are linked together, be equipped with the ball valve between the export of elasticity module and high-pressure oil duct, the fuel pressure that the ball valve passes through in the high-pressure oil duct is with control intercommunication or closed. In the lifting process of the needle valve, the dynamic compensation of the fuel injection flow can be realized, so that the fuel injection quantity in unit time can be improved, the cavitation phenomenon in the fuel nozzle is reduced, and the service life of the fuel injector is prolonged while the working performance of the fuel injector is improved.

Description

Needle valve matching part of common rail fuel injector

Technical Field

The invention relates to the technical field of oil injection systems, in particular to a needle valve matching part of a common rail oil injector.

Background

In the traditional high-pressure common rail fuel injector, a needle valve matching part is the most key structural component in the whole fuel supply system. When high-pressure fuel flows into the fuel injection nozzle from the needle valve body pressure chamber, the fuel pressure is greatly reduced due to the rapid change of the flow cross section area and the flow direction of the fuel, so that the serious cavitation phenomenon is generated on the upper surface of the fuel injection nozzle, the surface cavitation is generated in the long term, the service life of the fuel injector is shortened, and the fuel injection characteristic, the working stability and the safety of the fuel injector are seriously influenced. With the continuous increase of the oil injection pressure of the common rail system, when fuel oil flows through the conical surface of the needle valve and the inlet of the oil nozzle, the pressure and flow loss generated by the fuel oil are more and more serious, so that the injection capability of the oil injector is reduced, and the overall working performance of the oil injection system is influenced.

The currently adopted improvement method mainly comprises the steps of increasing the number of oil injection holes, adjusting the injection angle of the oil injection holes, changing the aperture size of the oil injection holes and the like. Although the method can reduce the flow loss to a certain degree, the method is difficult to meet the actual requirements under specific engineering application and limits the actual application scenes. In addition, the generation of the internal cavity of the fuel injection nozzle cannot be effectively inhibited, so that the flow coefficient of the fuel injection nozzle cannot be improved to improve the injection performance of the fuel injector.

Disclosure of Invention

The invention aims to provide a needle valve matching part of a common rail oil sprayer, which can realize dynamic compensation of fuel injection flow in the lifting process of a needle valve, thereby improving the oil injection quantity in unit time, simultaneously lightening the cavitation phenomenon in an oil nozzle, and improving the working performance of the oil sprayer and prolonging the service life of the oil sprayer. In order to achieve the purpose, the invention adopts the following technical scheme:

a needle valve matching part of a common rail fuel injector comprises a needle valve, a needle valve body and an elastic module, wherein the needle valve is positioned in the needle valve body, a pressure chamber is formed between the inside of the needle valve body and the bottom of the needle valve, a plurality of oil injection holes are arranged at the bottom of the needle valve body and are arranged along the circumferential direction of the pressure chamber, the aperture of the oil spray hole is gradually reduced from inside to outside, the cross section of the oil spray hole is elliptic, the elastic module is arranged at the bottom of the needle valve, a plurality of oil outlets distributed along the circumferential direction are arranged around the elastic module, a high-pressure oil duct is arranged in the needle valve, the outlet of the high-pressure oil duct is communicated with the oil outlet holes, and a ball valve is arranged between the elastic module and the outlet of the high-pressure oil duct and is communicated or closed under the control of the fuel pressure in the high-pressure oil duct.

Optionally, the elasticity module includes spring holder and preload piece, the spring holder sets up the bottom of needle valve, the top of spring holder is equipped with preload piece, preload piece with the butt has between the export of high pressure oil duct the ball valve.

Optionally, when the needle valve descends to be completely closed with the needle valve body, the outlets of the oil outlet holes are located inside the pressure chamber.

Optionally, the number of the oil outlet holes is equal to the number of the oil injection holes.

Optionally, a plurality of outlets of the oil outlet holes and inlets of the oil injection holes are arranged in a one-to-one correspondence manner.

Optionally, an angle between the first wall surface of the pressure chamber and the inner side wall surface of the oil injection hole connected with the first wall surface is α, and a is in a range of 145 ° < α < 160 °.

Optionally, an included angle between the inner sidewall surface of the oil spray hole and a center line of the oil spray hole is β, and a value range of β is greater than 7 ° and less than 10 °.

Optionally, a ratio of a long axis b to a short axis a of a cross-sectional normal projection of the oil spray hole is b/a, and a value range of b/a is 1.3-1.7.

Optionally, the extending direction of the long axis b is parallel to the vertical direction or parallel to the horizontal direction.

Optionally, the preload member is a preloaded spring.

Compared with the prior art, the invention has the beneficial effects that: because the ball valve is arranged between the elastic module and the outlet of the high-pressure oil duct and is controlled to be communicated or closed through the fuel pressure in the high-pressure oil duct, the dynamic compensation of the fuel injection flow is realized in the lifting process of the needle valve, and the fuel injection quantity in unit time is improved; and because the aperture of the oil spray hole is gradually reduced from inside to outside and the cross section of the oil spray hole is oval, the pressure drop of the oil spray hole is reduced, the cavitation effect inside the oil spray nozzle is reduced, and the service life of the oil spray nozzle is prolonged while the working performance of the oil spray nozzle is improved.

Drawings

FIG. 1 is a schematic cross-sectional view of a needle coupling for a common rail fuel injector in accordance with an embodiment of the present invention;

FIG. 2 is an enlarged schematic view of FIG. 1 labeled A;

fig. 3 is a partially enlarged view of fig. 2 in the direction B.

Reference numerals:

1-a needle valve, 2-a needle valve body, 3-an oil injection hole, 4-a pressure chamber, 5-a first wall surface and 6-an inner side wall surface of the oil injection hole; 7-spring seats; 8-oil outlet holes; 9-preload pieces; 10-ball valve; 11-high pressure oil gallery.

Detailed Description

In order to make the technical problems solved, the technical solutions adopted and the technical effects achieved by the present invention clearer, the technical solutions of the present invention are further described below by way of specific embodiments with reference to the accompanying drawings.

It is explained in advance that the cavitation phenomenon is a process of formation, development and collapse of vapor or gas cavities in the liquid or at the liquid-solid interface when the local pressure in the liquid is reduced. The pressure drop at the oil spray hole of the traditional oil spray nozzle is large, so that the cavitation phenomenon is easily caused, and after the oil spray nozzle is subjected to cavitation impact in the oil spray process, the surface of the oil spray nozzle can be deformed and the material is degraded, so that the flow coefficient of the oil spray nozzle is reduced, and the oil spray characteristic, the stability and the service life of the oil spray nozzle are influenced.

The included angle between the first wall surface of the alpha-pressure chamber and the inner side wall surface of the oil injection hole is formed; the included angle between the inner side wall surface of the beta-oil spray hole and the central line thereof; the gamma-oil injection angle is the included angle between the central line of the oil injection hole and the central axis of the needle valve body; a-the length of the minor axis of the normal projection of the elliptical cross section; b-major axis length of the normal projection of the elliptical cross section.

The specific structure of the needle coupling member of the common rail injector according to the embodiment of the invention will be described with reference to fig. 1 to 3.

The utility model provides a common rail injector's needle valve idol piece, includes needle valve 1, needle valve body 2 and elasticity module, needle valve 1 is located needle valve body 2, forms pressure chamber 4 between needle valve body 2's the inside and the bottom of needle valve 1, and the bottom of needle valve body 2 is equipped with a plurality of nozzle opening 3, and a plurality of nozzle opening 3 set up along pressure chamber 4's circumferential direction, and the aperture of nozzle opening 3 diminishes gradually just from inside to outside the transversal ellipse of personally submitting of nozzle opening 3, and the elasticity module sets up the bottom at needle valve 1, is equipped with a plurality of oil outlet 8 along the circumferential direction distribution around the elasticity module, is equipped with high-pressure oil duct 11 in the needle valve 1, and the export and a plurality of oil outlet 8 of high-pressure oil duct 11 are linked together, is equipped with ball valve 10 between the export of elasticity module and high-pressure oil duct 11, and fuel pressure in ball valve 10 passes through high-pressure oil duct 11 is with control intercommunication or closed.

In the above embodiment, the flow dynamic compensation process principle is as follows: when the needle valve 1 is in a descending motion process, the pressure in the pressure chamber 4 is gradually reduced, so that the generated flow loss is gradually increased, meanwhile, the pressure difference between the lower end face and the upper end face of the ball valve 10 is gradually increased, so that the ball valve 10 moves downwards, the flow of fuel oil passing through the oil outlet 8 is gradually increased and flows to the corresponding oil nozzle, and the flow loss in the oil nozzle caused by pressure drop is compensated; when the needle valve 1 is in the process of rising movement, the pressure in the pressure chamber 4 is gradually increased, and further the pressure difference between the lower end face and the upper end face of the ball valve 10 is gradually reduced, so that the ball valve 10 moves upwards, the fuel flow passing through the oil outlet 8 is gradually reduced, and the dynamic compensation process of the fuel flow is realized.

In addition, the needle valve coupling of the common rail injector of the above embodiment can make the fuel flow into the injection hole 3 from the pressure chamber 4, and increase the flow cross-sectional area of the fuel flowing through the injection hole 3 under the condition of satisfying the injection angle γ (the injection angle is determined by the included angle γ between the central line of the injection hole 3 and the central axis of the needle valve body 2) and the unchanged injection rate, and by reasonably setting the change of the flow cross-section of the injection hole 3, that is, the aperture of the injection hole 3 gradually decreases from inside to outside and the cross-section of the injection hole 3 is elliptical, the injection pressure drop decreases, thereby significantly inhibiting the cavitation generated on the inner side wall surface 6 of the injection hole, improving the flow coefficient of the injection nozzle, reducing the fuel flow loss, and improving the service life of the injector body and simultaneously improving the injection characteristic, the working stability and the safety of the injector.

In conclusion, the needle valve matching part of the common rail injector of the embodiment can realize dynamic compensation of fuel injection flow in the lifting process of the needle valve 1 so as to make up for throttling loss caused by the inherent structure of the needle valve matching part, thereby improving the injection quantity in unit time, simultaneously lightening the cavitation effect in the injection nozzle, and improving the working performance of the injector and prolonging the service life of the injector.

Optionally, the elastic module comprises a spring seat 7 and a preload piece 9, the spring seat 7 is arranged at the bottom end of the needle valve 1, the preload piece 9 is arranged above the spring seat 7, and a ball valve 10 is abutted between the preload piece 9 and an outlet of the high-pressure oil passage 11. It can be understood that the position relationship and the cooperation mode among the spring seat 7, the preload member 9 and the ball valve 10 are beneficial to the descending and ascending movement of the ball valve 10 under different working conditions, so that the dynamic compensation process of the fuel flow is realized.

Specifically, the preload piece 9 can be a preload spring, and has good elastic force effect and low cost. Of course, in other embodiments of the present invention, other selections may be made according to actual needs.

Alternatively, when the needle valve 1 descends to be completely closed with the needle valve body 2, the outlets of the oil outlet holes 8 are all located inside the pressure chamber 4.

Optionally, the number of the oil outlet holes 8 is equal to the number of the oil injection holes 3; the outlets of the oil outlet holes 8 and the inlets of the oil injection holes 3 are arranged in a one-to-one correspondence mode.

In the above embodiment, the diameter of the oil injection hole 3 is gradually reduced from the inside to the outside, which is advantageous in further reducing the pressure drop due to the change in the sectional area, thereby suppressing the formation of the cavity. In addition, the cross section of the oil injection hole 3 is elliptical, so that the requirement of actual working conditions can be better met, and the area generated by cavitation can be further reduced; the aperture of the oil spray hole 3 of this embodiment is gradually reduced from inside to outside and penetrates through the whole oil spray hole 3, and the fuel circulation characteristic is not influenced when the light cavitation degree is reduced.

In some preferred embodiments, the angle between the first wall 5 of the pressure chamber and the inner side wall 6 of the nozzle bore to which it is connected is α, which is in the range 145 ° < α < 160 °. It can be understood that the included angle between the inner side wall surface 6 of the oil injection hole and the first wall surface 5 of the pressure chamber 4 is an obtuse angle between 145 degrees and 160 degrees, which not only can ensure that the direction change of fuel oil flowing into the inlet of the oil injection nozzle is gentle, but also can avoid the reduction of the fuel oil flowing section when the needle valve 1 and the needle valve body 2 are closed due to the overlarge included angle alpha, thereby influencing the flow performance when the fuel oil flows through the conical surface of the needle valve 1, and also can avoid the cavitation phenomenon of the inner side wall surface 6 of the oil injection hole due to the undersize included angle alpha; in addition, the advantage is that the formation of cavitation on the surface of the oil nozzle can be obviously inhibited without changing the oil injection angle.

Optionally, an included angle between the inner side wall surface 6 of the oil spray hole and the center line of the oil spray hole 3 is β, and the value range of β is 7 ° < β < 10 °. In the value range, the injection performance of the oil nozzle is prevented from being reduced due to the overlarge included angle beta under the condition that the cross section of an inlet of the oil nozzle is increased and the oil injection quantity is unchanged when the angle beta is 0 degrees compared with the traditional angle beta.

Optionally, the ratio of the long axis b to the short axis a of the cross-sectional normal projection of the oil spray hole 3 is b/a, and the value range of b/a is 1.3-1.7. In the value range, the distribution area of the cavities on the inner side wall surface 6 of the oil injection hole is reduced relative to the traditional injection hole (beta is 0 degrees), and meanwhile, the circulation performance of fuel oil in the oil injection hole 3 is not influenced.

Specifically, the long axis b of the cross-section normal projection of the oil spray hole 3 can be selected to be arranged along the vertical direction, can also be selected to be arranged along the horizontal direction, or can be arranged in other directions, and the long axis b and the short axis a are ensured to be perpendicular to each other.

In conclusion, the needle valve matching part of the common rail oil sprayer obviously reduces the pressure drop caused by the obvious change of the flowing direction of the fuel oil by increasing the included angle between the inner side wall surface 6 of the oil spray hole and the first wall surface 5 of the pressure chamber, thereby weakening the generation of cavities in the upper surface area of the oil spray nozzle; by adopting the oil nozzle structure with the gradually reduced hole diameter from inside to outside, the flow cross section area of the fuel oil flowing through the oil injection hole 3 can be increased under the condition of ensuring that the oil injection rate is not changed, so that the pressure drop generated by the change of the cross section area is further reduced, and the generation of cavities is effectively inhibited; the oil injection hole 3 with the cross section of the elliptical structure can reduce the size of the area for generating the cavity from the physical structure, thereby further weakening the physical mechanism for generating cavitation, ideally inhibiting the cavitation phenomenon, improving the oil injection efficiency of an oil injection nozzle, prolonging the service life of the needle valve matching part of the oil injector and improving the economic benefit.

It should be noted that the included angle α between the inner sidewall surface 6 of the oil injection hole and the first wall surface 5 of the pressure chamber, the included angle β between the inner sidewall surface 6 of the oil injection hole and the center line thereof, and the ratio b/a of the major axis to the minor axis of the normal projection of the elliptical cross section of the oil injection hole 3 may be approximated according to the actual operating conditions, and are not particularly limited.

In the description herein, references to the description of "some embodiments," "other embodiments," or the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Further, it is to be understood that the terms "upper", "lower", "inner", "outer", "vertical", "horizontal", and the like, as used herein, refer to an orientation or positional relationship based on that shown in the drawings, which is for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

In the present invention, unless otherwise expressly stated or limited, the terms "connected," "mounted," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other suitable relationship. Those skilled in the art can understand the above specific meanings included in the present invention according to specific situations.

Furthermore, features defined as "first" and "second" may explicitly or implicitly include one or more of the features for distinguishing between descriptive features, non-sequential, non-trivial and non-trivial. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

The above description is only a preferred embodiment of the present invention, and for those skilled in the art, the present invention should not be limited by the description of the present invention, which should be interpreted as a limitation.

Claims

1. A needle valve matching part of a common rail fuel injector is characterized by comprising a needle valve, a needle valve body and an elastic module, the needle valve is positioned in the needle valve body, a pressure chamber is formed between the inside of the needle valve body and the bottom of the needle valve, the bottom of the needle valve body is provided with a plurality of oil injection holes which are arranged along the circumferential direction of the pressure chamber, the aperture of the oil spray hole is gradually reduced from inside to outside, the cross section of the oil spray hole is elliptic, the elastic module is arranged at the bottom of the needle valve, a plurality of oil outlets distributed along the circumferential direction are arranged around the elastic module, a high-pressure oil duct is arranged in the needle valve, the outlet of the high-pressure oil duct is communicated with the oil outlet holes, and a ball valve is arranged between the elastic module and the outlet of the high-pressure oil duct and is communicated or closed under the control of the fuel pressure in the high-pressure oil duct.

2. The needle valve matching part of the common rail injector according to claim 1, wherein the elastic module comprises a spring seat and a pre-tightening piece, the spring seat is arranged at the bottom end of the needle valve, the pre-tightening piece is arranged above the spring seat, and the ball valve is abutted between the pre-tightening piece and the outlet of the high-pressure oil passage.

3. The needle coupling member of a common rail injector according to claim 1, wherein the outlet ports of the oil outlet holes are located inside the pressure chamber when the needle valve descends to be completely closed with the needle valve body.

4. The needle coupling member of a common rail injector according to claim 1, wherein the number of the oil outlet holes and the number of the injection holes are equal.

5. The needle valve coupler of a common rail injector according to claim 4, wherein outlets of the plurality of oil outlet holes and inlets of the oil outlet holes are provided in one-to-one correspondence.

6. The needle and coupler for a common rail injector according to claim 1, wherein an angle α between a first wall surface of said pressure chamber and an inner side wall surface of said injection hole to which said pressure chamber is connected is in a range of 145 ° < α < 160 °.

7. The needle coupling member of a common rail injector according to claim 6, wherein an angle between said inner side wall surface of said injection hole and a center line of said injection hole is β, and a range of β is 7 ° < β < 10 °.

8. The needle valve matching part of the common rail injector according to claim 1, wherein a ratio of a major axis b to a minor axis a of a cross-sectional normal projection of the injection hole is b/a, and a value of b/a is in a range of 1.3. ltoreq. b/a. ltoreq.1.7.

9. The needle coupling member of a common rail injector according to claim 8, wherein the long axis b extends in parallel with a vertical direction or in parallel with a horizontal direction.

10. The needle coupling for a common rail fuel injector of claim 2, wherein the preload member is a preloaded spring.